Process for preparing olefin hydrocarbons for detergent use



United States Patent 3,409,703 PROCESS FOR PREPARING OLEFIN HYDRO- CARBONS FOR DETERGENT USE Robert M. Engelbrecht, St. Louis, Raymond A. Franz, Kirkwood, Richard N. Moore, St. Louis, James M. Schuck, Webster Groves, and Robert G. Schultz, Vinita Park, Mo., assignors to Monsanto Company, a corporation of Delaware No Drawing. Filed Nov. 26, 1963, Ser. No. 326,197 9 Claims. (Cl. 260-68315) The present invention relates to a process for the prep aration of olefin hydrocarbons having particular utility in the preparation of detergent compositions. The present invention also relates to a process for the preparation of alkyl aromatic compounds useful in the detergent industry. More particularly, the present invention relates to a process for the preparation of olefin hydrocarbons and to their ultimate use in the production of alkyl aromatic compounds for detergent use, said alkyl aromatic compounds being susceptible to biological decomposition.

In this country, as well as in many foreign countries, the most extensively used of all synthetic detergents are the aromatic su'lfonic acids. Of the aromatic sulfonic acid synthetic detergents, the most widely used and accepted are the alkylbenzene sulfonates. These detergent compounds combine relatively good detergent properties with relatively inexpensive production. The alkylbenzene sulfonates, to a large extent, derive their alkyl substituents from olefin polymers, with the most commonly used olefin polymers being propylene tetramers, pentamers, and fractions intermediate between these two. These propylene polymers are produced, generally, by the direct polymerization of propylene over phosphoric acid catalysts to the tetramer, pentamer, etc.

The alkylbenzene sulfonates derived from propylene tetramers, pentamers and fractions intermediate between these two, though having excellent detergent properties as well as being relatively inexpensive to manufacture, have in recent years began creating a significant problem. These alkylbenzene sulfonates are highly resistant to biological oxidation, or as otherwise known, biodegradation. Because of the resistance of these alkylbenzene sulfonate detergents to biological decomposition, considerable amounts of detergent compound pass through sewage or waste disposal plants unchanged. The presence of the undecomposed detergent in the effiuent from these treating plants, Where the efiluent is passed into streams, rivers or lakes, is responsible for unsightly nuisances in the form of foam and scum and represents potential toxicity hazards to aquatic life and to communities downstream. Further the resistance of the presently known alkylbenzene sulfonates to decomposition causes considerable difliculty in operating the sewage and waste disposal plants.

The problem of the resistance of present day alkyl aromatic sulfonates to biological decomposition is receiving rapidly increasing attention from public health officials, sanitary engineers and the detergent industry. In several countries of Europe the problem has become so acute as to inspire governmental action relative to the control of the manufacture of alkyl aromatic sulfonate detergents. Several states in this country or seriously considering the problem created by the nonbiodegradable alkyl aromatic sulfonates.

The present invention has as one of its objects to provide a process for preparing polymeric olefin hydrocarbons particularly suited for the preparation of detergent compositions susceptible to biological decomposition. Another object of the present invention is to provide a process for preparing biodegradable detergent compositions. Still another object of the present invention is to provide a process for the preparation of alkyl aromatic sulfonate compositions which are biodegradable. An additional object of the present invention is to provide a biodegradable alkyl aromatic sulfonate composition. Additional objects will become apparent from the following description of the invention herein disclosed.

The present invention comprises subjecting normally gaseous mono-olefin hydrocarbons to elevated temperatures and pressures in a thermal reaction zone and in the presence of a modifying agent which under the conditions of the thermal reaction zon will decompose or otherwise form hydrogen chloride, hydrogen bromide, hydrogen iodine, hydrogen sulfide or a combination thereof, thereby forming a polymer fraction, separating said polymer fraction to obtain a fraction comprised of relatively linear dimers of the normally gaseous mono-olefin hydrocarbons, said dimers having 4 to 8 carbon atoms, contacting said relatively linear dimer fraction in a second polymerization zone at a temperature of 50 to 250 C. and a pressure of atmospheric to 2,500 p.s.i.g. with an activated carbon supported cobalt oxide catalyst activated at a temperature of 400 to 575 C. to form a second polymer fraction, separating said second polymer fraction to obtain a fraction comprised of relatively linear mono-olefin dimers of olefin hydrocarbons in the feed to the second polymer fraction, said dimers being of 8 to 16 carbon atoms. To prepare an alkyl aromatic sulfonate, the second stage dimers of 8 to 16 carbon atoms are reacted with an aromatic compound in the presence of an alkylation catalyst under alkylating conditions to form an alkyl aromatic compound and then said alkyl aromatic compound is sul-fonated and subsequently neutralized thereby producing an aromatic sulfonate more susceptible to biological decomposition than those prepared by presently known processes.

Though the above embodiment contemplates the use of the relatively linear olefin dimer fraction of 8 to 16 carbon atoms in the alkylation of an aromati compound for the ultimate production of an alkyl aromatic sulfonate, the present invention is not to be so severely limited. This olefin fraction may be used in the preparation of any detergent composition which requires an alkyl substituent of 8 to 16 carbon atoms. For example, the olefin fraction is useful in the preparation of alkyl sulfonates in which the alkyl group is directly connected to the sulfonate radical or in which the alkyl group is connected to the sulfonate radical by an intermediate linkage such as an ester, ether, amide, or like groups. Also, this olefin fraction is useful in preparing alkyl aromatic sulfonates in which the alkyl group is joined to the aromatic nucleus through intermediate linkages such as ester, ether, amide and like groups.

The term dimer as used herein refers to those polymers obtained by the condensation of two and only two molecules or monomer units of mono-olefinic hydrocarbons. These molecules or monomer units may be like or unlike. For example, dodecenes produced by the condensation of two hexene-l molecules or the condensation of a butene-l molecule and an octene-l molecule are equally within the meaning of the term dimer as used herein.

For purposes of simplifying the description of the present invention, the themal polymerization of normally gaseous mono-olefin hydrocarbons, briefly described above, will be hereinafter referred to as the first stage dimerization and the dimer product obtained from this first stage dimerization as the first stage dimer. The polymer? ization of the first stage dimer, also briefly described above, is hereinafter referred to as the second stage dimerization and the dimer product obtained from this second stage dimerization as the second stage dimer.

The first stage dimerization step of the present process dimerizes normally gaseous mono-olefin hydrocarbons.

The normally gaseous mono-olefin hydrocarbons are ethylene, propylene and butylenes. The feed to the first stage dimerization may contain only one of these mono-olefins or it may contain a mixture of two or more. When two or more of these mono-olefins are present, both pure dimerization and codimerization will take place. For example, if the feed comprises ethylene and propylene, then ethylene dimers of 4 carbons and propylene dimers of 6 carbon atoms will be formed and also ethylene-propylene codimers of carbon atoms will be formed. If the normally gaseous mono-olefin feed includes butylenes, it is usually preferred that the butylenes be n-butylenes. Further, it is preferred that the n-butylene be terminally unsaturated. The preferred feed to the first stage dimerization is propylene. Though it is generally preferred to have a relatively pure normally gaseous mono-olefin hydrocarbon feed to the first stage dimerization, it is not altogether necessary. The feed may contain small amounts of mono-olefins other than the normally gaseous monoolefins. However, since the primary purpose of the first stage dimerization is to produce dimers of 4 to 8 carbon atoms, the amount of other polymerizable mono-olefins present in the feed should be kept to a minimum. The presence of diolefins and triolefins as well as acetylenic compounds in the feed is to be avoided. However, small amounts of such materials, below approximately 0.1 percent by weight of the feed may be tolerated. Saturated hydrocarbons as well as other inert materials may be present in tthe feed to a considerable extent. Such materials have no deleterious effect on the dimerization reaction. However, as a practical matter, large quantities of these materials are to be avoided since they are merely dead weight of the process and needlessly increase the cost of handling the feed materials and products.

20,000 p.s.i.g. A preferred upper pressure limit is 5,000 p.s.i.g. The optimum pressures for carrying out the present invention generally may be stated as the minimum pressure obtained as the sum of the partial pressures of 5 the reactants within a closed polymerization zone, at the mately 0.001 to 240 minutes. However, a preferred residence time range is from 0.05 to 120* minutes.

The modifying agents useful in the first stage dimerization of the present invention comprise materials which under the conditions of the thermal reaction zone will de- 0 compose or otherwise form hydrogen chloride, hydrogen bromide, hydrogen iodine, hydrogen sulfide or combinations thereof. The term agent is meant to include, in the sense used herein, elemental sulfur, chlorine, bromine and iodine gas as Well as chemical compounds of which these elements are a part. The compounds which contain chlorine, bromine, iodine or sulfur may be either organic or inorganic compounds and may contain in addition to these elements such other elements as carbon, hydrogen, oxygen, or nitrogen. If the compound is an organic compound it may be saturated or unsaturated, aliphatic or aromatic, straight-chain, branched-chain or cyclic in structure. Among the halogen containing compounds within the scope of the present invention are the following nonlimiting examples:

Z-bromopropane 2-chloropropane. l-iodopropane... l-bromobutane..-

l-bromopentane Q-bromopentane- 3-chloropentane. 2-iodopentane. 3-bromohexane 2-iodohexane 2-bromo4-methylhexane. S-chloroheptane 3-bromoheptane Z-iodoheptane Hydrogen iodide The first stage dimerization by the thermal polymerization of mono-olefin hydrocarbons is carried out at elevated temperatures, usually within the range of 250 C. to the cracking temperature of the particular hydrocarbons in the feed. The preferred temperatures for operating the present invention are, however, within the range of from about 300 to 500 C. Temperatures of 325 to 475 C. will be found to provide the optimum in yield of dimer product. Pressures at which this first stage polymerization is carried out are generally greater than 200 p.s.i.g. The upper limit for pressures in carrying out the present invention has no critical limitation other than the strength of the reaction vessel. Generally, it may be stated that the higher the pressure the better the results of the polymerization reaction. Preferred pressures for operating the present first stage dimerization are above 1,000 p.s.i.g. Seldom will the upper limit of the pressure range be above p Dichlor0benzene p-Chlorotoluene.

m-B romot oluene.

. m-Bromo-chlorobenzene Iodine gas Bromobenzene Chloroethanoic acid.

Ohlorob enzene m-Dichlorobenzene. o-Dichlorobenzene.

Dibromoethanoic acid. di-Iodoethanoie acid.

a-Chloroacetamide.

a.Bromoacetani1ide.

m-Dibromobenzene- Benzoyl chloride.

o-Dibromobenzene Benzoyl bromide.

-Dibromobenzene. Benzoyl iodide.

odobenzene Butanoyl chloride. o-Iodotoluene-.. Butanoyl bromide. m-Iodotolueue. Butanoyl iodide. p-Iodotoluene. 2-chl0ro l, 4-benzenediol.

o-Chlorotoluene.

2-bromo-1-, 4 benzenediol. m-clilorotoluene l-chloro-4-nitronaphthalene. Benzene carbonyl chloride. Benzene carbonyl bromide. Succinyl chloride. 4-Chloroquinoline. Ethanoyl iodide.

Hexanoyl chloride.

Decanoyl chloride.

p-B romo-chlorobenzene Z-Bromoethanol.

o-Bromotoluene 2-Bromonaphthalene... 2-Chloroethanol.

l-Chloronahpthalcne bis-B-chloroethylether. 1, 3 dichloronaphthalene Chloromethoxy methane. 2-Bromodipheny1 Cyclohexylchloridc. Z-Chlorodiphenyl Cyclohexylbromide.

4-Ch1orodipheny Chlorine gas Bromine gas.

Carbon tetrachloride. 2-chloro-3-hexene. 2-bromo2-pentene. 3-bromo4-octene.

The halogen containing compounds most useful in the 0 practice of the present invention are those which contain a halogen from the group consisting of bromine, chlorine and iodine and the elements carbon and/or hydrogen. These compounds are the halogen substituted hydrocarbons and hydrogen halides. There is no critical limit to 5 the molecular weight of the modifying compound other ferred. In the practice of the present invention, the preferred halogen compounds are the monoand di-halogen substituted hydrocarbons of no more than 6 carbon atoms and the hydrogen halides. Though all of the halogens from the group consisting of bromine, chlorine and iodine are operable in the present invention, it is generally preferred to use those compounds containing chlorine and bromine with bromine being preferred over chlorine.

Among the sulfur-bearing compounds useful in the present invention are the following nonlimiting examples:

allyl sulfide benzyl disulfide 2-methyl-1-butanethiol 2-methyl-2-butanethiol butyl disulfide 1,2-ethanedithiol ethylene sulfide ethyl sulfide l-heptanethiol isoamyl disulfide isobutyl sulfide methyl sulfide l-naphthalenethiol phenyl disulfide 2-methyl-1-propanethiol 2,2-thiodiethano1 acetyl disulfide benzyl sulfide 3-methyl-1-butanethiol tert-octanethiol butylsulfide ethanethiol ethyl disulfide furfuryl mercaptan l-hexanethiol isoamyl sulfide methyl disulfide Z-naphthalenethiol l-pentanethiol l-propanethiol 2-propanethiol thiophene benzenesulfonic acid p-bromo-benzenesulfonic o-bromo-benzenesulfonic acid acid o-formyl-benzenesulfonic p-chloro-benzenesulfonic acid acid benzyl sulfoxide octyl sulfate sulfide bis-(B-dichloroethyDsulfide ethyl methyl sulfide tetradecyl sulfate thionaphthene Z-methylthiophene a-methylthiophene sulfur dissolved in dialkyl alkanol amines methanethiol thionaphthenequinone 3-methylthiophene elemental sulfur ethyl sulfuric acid benzoyl disulfide As noted from the above list of compounds, the sulfur bearing modifying agents may contain such elements other than sulfur as carbon, hydrogen, oxygen, nitrogen, chlorine, bromine, iodine, and the like. Among the preferred modifying compounds are sulfur and such sulfur bearing compounds as mercaptans or thiols both aliphatic and aromatic, hydrogen sulfide and thio ethers. Also within this list of preferred compounds are those derived from dissolving sulfur in tertiary amines at elevated temperatures. The preferred modifying compounds are sulfur and sulfur bearing compounds containing the additional elements of carbon and/or hydrogen. When using sulfur bearing compounds containing carbon and hydrogen, it is generally preferred that they contain no greater than 20 carbon atoms with those containing less than carbon atoms being more preferred.

It is, of course, not necessary that the modifying agent be limited to a compound which will form one of the above mentioned hydrogen halides or a sulfur compound which will form hydrogen sulfide. It is within the scope of the present invention that a combination of the two types of compounds may be used. For example, the present invention contemplates the use in combination as a modifying compound such compounds as bromo propane and benzyl mercaptan. Also, one compound may contain both a halogen atom and a sulfur atom and may suffice as a combination modifying agent. Such an example is 2-bromothiophene.

The amount of the modifying agent used in the first stage dimerization is based on the ratio of hydrogen halide or hydrogen sulfide obtainable by decomposition of formation to the polymerizable mono-olefin hydrocarbons in the feed. Generally, the amount of modifying agent present in the reaction chamber will range from approximately 1:10 to 1:500 mols of the modifying agent, as a hydrogen halide or hydrogen sulfide, per mol of monoolefin hydrocarbon in the feed. A preferred mol ratio, however, is within the range of from approximately 1:50 to 1:100.

The method whereby the modifying compound is added to the dimerization zone in the first stage dimerization is not critical to the present invention and may be added in virtually any manner. The only critical feature of this addition is that there be a thorough intimate contact between the monoolefin hydrocarbon and the modifying agent. The modifying agent may be introduced countercurrent or crosscurrent to the flow of the feed. Further, when using liquid or liquefiable modifying agents, they may be dispersed within the reaction chamber either as a liquid bed or dispersed upon heat exchange pellets and the like. The best method whereby the modifying agent is brought into contact with the reaction will, of course, as a practical matter, vary with the physical properties of the modifying agent. For example, a gaseous or gasified modifying agent would most likely be advantageously introduced concurrent, crosscurrent or countercurrent to the feedstream whereas a liquid or liquefiable solid might more advantageously be placed within the reaction chamber as a dispersed bed as above described.

The feeds to the second stage dimerization reaction are the relatively linear mono-olefinic dimer products of the first stage dimerization. These dimer products are of 4 to 8 carbon atoms depending upon the normally gaseous mono-olefin hydrocarbons in the feed to the first stage dimerization. If the preferred normally gaseous monoolefin hydrocarbon, propylene, is the feed to the first stage dimerization, then the dimer feed to the second stage dimerization is ordinarily of 6 carbon atoms. It is preferred that the dimer feed to the second stage dimerization be substantially linear mono-olefin hydrocarbons. However, the presence of branched-chain mono-olefins up to a concentration of 15% by weight of the feed to the second stage dimerization is not deleterious to the present invention. A particularly preferred mono-olefin dimer feed to the second stage dimerization is one which contains no greater than 10% by weight of branched-chain monoolefin hydrocarbons with the remainder of the monoolefins being straight-chain. The mono-olefin hydrocarbons in the feed to the second stage dimerization include both internally and terminally unsaturated mono-olefin hydrocarbons. Since the feed to the second stage dimerization is a product of the first stage dimerization, there will generally be fewer impurities such as diolefins, triolefins, saturated hydrocarbons, inert materials and the like than are in the feed to the first stage dimerization. Further, since in most instances, the product from the first stage dimerization is subjected to a separation step to recover the dimers produced and to exclude excess branchedchain mono-olefins, most of the impurities such as those above mentioned may, if present, also be removed during this separation step.

The separation step used for purifying the product of the first stage dimerization to meet the above discussed feed requirements of the second stage dimerization may be carried out by any conventional means. Generally, ordinary fractional distillation will be adequate for effecting the purification of the dimer product of the first stage dimerization. The determination of the precise fractionation esuipment and conditions for obtaining the second stage dimerization feed, is well within the ability of those skilled in the art having the above definition of this feed before them. When the preferred feed, propylene, is dimerized in the first stage dimerization, fractionation of the dimer product to obtain an overhead fraction having a boiling range of approximately 60 to 75 C. will usually provide a suitable feed for the second stage dimerization. In addition to or in place of fractional distillation, other conventional separation or purification means such as adsorbents, i.e., molecular sieves, solvent extraction, extractive distillation, selective polymerization, isomerization and the like may be employed to conform the dimer product of the first stage dimerization to the feed requirements of the second stage dimerization. To repeat, it is immaterial to the present invention what separation means is used for purifying the product of the first stage dimerization to meet the feed requirements of the second stage dimerization, so long as such separation means provides the desired purification.

One of the primary advantages found in the herein disclosed first stage dimerization process is found in its production of relatively large quantities of dimers meeting the above defined feed requirements to the second stage dimerization. The amount of second stage dimerization feedstock produced by the first stage dimerization is significantly improved over other conventional processes. To meet the above defined second stage feed requirements, it is generallynecessary to remove a portion of the branched-chain dimers by such means as fractionation. Many of the isomeric branched-chain dimers are exceptionally difficult to separate from the straight-chain dimers by ordinary separation means such as fractionation. The first stage dimerization process of the present invention produces significantly less of these difiicultly separable branched-chain isomers than do other known polymerization processes.

The base supports useful in the catalyst used in the second stage dimerization are activated carbons. These activated carbons may be any porous carbon known to be useful for catalyst preparation. The activated carbons generally have surface areas of about 400 to 2,000 square meters per gram and may be in the form of compact masses, granules, chips, powders, etc. Suitable supports include coconut charcoal, Wood charcoal, carbon derived from coke, soft bone charcoal, hard bone charcoal, and the like. The ativated carbon may be obtained from animal, vegetable or petrolum sources and may include such commercial materials as Pittsburgh BPL, CAL, L, and SGL produced by Pittsburgh Coke and Chemical Co., Girdler G32C, and G32E produced by Chemical Products Division, Chemetron Corp, and Barnebey-Cheney Companys EE-l and EHl.

In preparing the activated carbon supported second stage dimerization catalyst, an activated carbon is impregnated with a solution of a cobalt salt and the salt subsequently converted to the oxide. This treatment of the activated carbon may be carried out by immersion of the carbon in the cobalt salt solution, by just moistening the carbon with the cobalt salt solution or by any other means known to those skilled in the art for impregnation of catalyst supports. The cobalt salt solution consists of a cobalt salt dissolved in any suitable solvent for the cobalt salt. Generally, wherever practical, aqueous or alcoholic solutions of the cobalt salt are used. Among the cobalt salts useful for impregnation of the activated carbon are the following nonlimiting examples: Cobalt acetate, cobalt sulfate, cobalt nitrate, cobalt butanoate, cobalt pentanoate, cobalt hexanoate, cobalt ammonium sulfate, cobalt arsenate, cobalt arsenite, cobalt carbonate, cobalt chromate, cobalt vanadate, cobalt molybdate, cobalt iodate, cobalt oxalate, cobalt citrate, cobalt sulfite and the like. The most useful cobalt salts are cobalt acetate, cobalt sulfate and cobalt nitrate in the cobaltous form with cobalt nitrate being the preferred salt. The cobalt salt solution is preferably an aqueous solution having a concentration calculated to give the desired amount of cobalt oxide on the activated carbon after activation of the catalyst.

Prior to treatment of the activated carbon with the cobalt salt solution, it is often preferred to pretreat the activated carbon to improve its efficacy. This pretreatment may take the form of an acid wash which, though not necessary, is a frequently desired pretreatment of activated carbons. If acid washed, it is preferred that the acid be an aqueous nitric acid. This aqueous nitric acid is preferably used in an amount of approximately 600 to 1000 ml. of acid per 500 ml. of activated carbon. It is generally preferred that the nitric acid be of a concentration of about 10 to 30% in water though it may be virtually any concentration. The acid wash, when used, ordinarily will be from 2 to 10 minutes in duration with 3 to 5 minutes generally being sufficient. After acid washing, the activated carbon is washed with water and if desired, dried.

In addition to or in place of acid washing, it is in many instances preferred to pretreat the activated carbon with a nonoxidizing gas or liquid. Usually, it is preferred that the activated carbon be dried previous to this form of pretreatment. When treating the activated carbon with a nonoxidizing gas, the gas is merely passed over the activated carbon, generally, at a temperature of to 500 C. for 0.5 to 8 hours. It is preferred that the nonoxidizing gas be passed over the'activated carbon at a temperature of 200 to 350 C. for 1 to 2 hours. The nonoxidizing gases include such gases as hydrogen, nitrogen, ammonia, helium, argon, and the like. These nonoxidizing gases may be used alone or in combination. It is preferred that the nonoxidizing gas, if used, be one selected from the group consisting of hydrogen, nitrogen, ammonia and combinations thereof with ammonia being preferred over the others. The nonoxidizing gases, when used, will generally be in the gaseous state; however, it is within the scope of the present invention to use the nonoxidizing gases in a liquefied form. Thus in referring to these nonoxidizing gases as gases, it meant that they are normally gaseous and not that they are limited to utilization in the gaseous form.

Among the nonoxidizing liquids which may be utilized in this pretreatment of the activated carbon are such compounds as ammonium hydroxide and the like. In most instances, the preferred nonoxidizing liquid is ammonium hydroxide. The nonoxidizing liquid is used in practically any concentration and the treatment carried out by immersing the dried activated carbon in the nonoxidizing liquid for a time sufiicient for complete absorption by the activated carbon of the maximum amount of the liquid absorbable by the carbon. In using the preferred nonoxidizing liquid, ammonium hydroxide, concentrations of 15 to 30% by weight in water preferably will be used. Generally, treatment of the activated carbon with a nonoxidizing liquid is at ambient temperatures (20 to 40 C.) though both higher and lower temperatures may be used.

The particularly preferred manner of treating the activated carbon prior to impregnation with cobalt salt is referred to as ammoniation and consists of pretreating the carbon with either ammonia or ammonium hydroxide or a combination thereof as described in the preceding paragraph. When both ammonia and ammonium hydroxide are used it is immaterial whether one or the other is used first followed by the other or whether they are used simultaneously.

The use of nonoxidizing gases and liquids in the treatment of activated carbon supported cobalt oxide catalysts is fully disclosed and claimed in copending application Ser. No. 294,750, filed July 12, 1963, now US. Patent No. 3,317,628, Ser. No. 229,192, filed Oct. 8, 1962, now abandoned, Ser. No. 254,433, filed Jan. 28, 1963, now US. Patent No. 3,333,016.

Though not necessary, it generally is desirable to have the activated carbon dry before it is treated with the cobalt salt solution. A particularly useful, but by no means limiting, manner of drying the activated carbon comprises heating the activated carbon at a temperature of 50 to 200 C. for 2 to 24 hours. A preferred method of drying the activated carbon comprises maintaining the carbon at a temperature of 100 to 150 C. for 2 to 6 hours. To facilitate drying, reduced pressures may be used. Of course, reduced pressures will shorten the drying period and/ or lower the temperatures.

After the activated carbon has been impregnated with the cobalt salt solution, the impregnated activated carbon is again subjected to a drying treatment. This drying treatment is carried out in the manner described in the preceding paragraph. It is not absolutely necessary that the catalyst be completely dried prior to activation. However, caution should be exercised in activating a catalyst which has not been subjected to at least partial drying. The drying step after impregnation brings about partial decomposition of the cobalt salt. Thus, if the catalyst has not been subjected to drying, there is a distinct possibility of overly rapid decomposition resulting in an explosion when the catalyst is subjected to activation.

Upon completion of the impregnation of the activated carbon with the cobalt salt, it is in some instances desirable, prior to activation, to subject the catalyst to treatment with a nonoxidizing gas or liquid such as with ammonia, ammonium hydroxide or a combination thereof. This treatment of the cobalt salt impregnated carbon with a nonoxidizing gas or liquid is carried out in the same manner and under the same conditions as is the treatment of the activated carbon alone with a nonoxidizing gas or liquid which has been hereinabove described. The treatment of the cobalt salt impregnated activated carbon with a nonoxidizing gas or liquid may be in addition to or instead of the pretreatment of the activated carbon prior to impregnation. The treatment of either the activated carbon or the cobalt salt impregnated activated carbon with the nonoxidizing gases and liquids is not necessary to the present invention and is not to be construed as limiting the present invention. This treatment merely reflects one of several modes of practice of the present invention.

The most critical feature in the preparation of the activated carbon supported cobalt oxide catalyst of the second stage dimerization is found in the activation of the catalyst. Activation is most often carried out at temperatures within the range of 400 to 575 C. with temperatures of 425 to 525 C. being preferred. Generally, a period of 0.5 to 3 hours is sufficient for complete activation of the catalyst. The catalyst activation is carried out in the presence of an inert atmosphere, i.e., helium, argon, carbon dioxide, propane, nitrogen and the like. Generally, it is preferred to use nitrogen as the inert atmosphere. Activation may be carried out at slightly reduced pressures if desired. If reduced pressures are used, it is preferred that the pressures not be reduced below 10 mm. Hg though lower pressures maybe used if desired.

Another feature of some importance in the second stage dimerization catalyst is the amount of cobalt present as cobalt oxide on the finished catalyst. The second stage dimerization catalyst may contain 2 to 50% by weight and higher of cobalt as an oxide. Generally, it is somewhat preferable to use a catalyst having the cobalt concentration, as the oxide, within a range of to 30% by weight of the total catalyst. For optimum dimerization activity in the second stage, the cobalt, as cobalt oxide, is present in the catalyst in an amount equivalent to 12 to 30% by weight of the finished catalyst.

The dimerization temperatures used in the second stage dimerization generally are within the range of from approximately 0 to 250 C. Usually, however, the second stage dimerization temperature is 100 to 200 C. Preferred temperatures for the second stage dimerization are within the range of approximately 125 to 200 C. Dimerization pressures in the second stage dimerization usually are within the range of from atmospheric pressure to 2,500 p.s.i.g. and higher. More often, however, pressures for the second stage dimerization are within the range of from approximately 10 to 400 p.s.i.g. with pressures of 100 to 300 p.s.i.g. preferred. The space velocity of the feed material in the catalyst zone of the second stage dimerization usually is within the range of 0.1 to 50 liquid volumes of feed per hour per volume of catalyst. Preferred space velocities for the second stage dimerization are within the range of from approximately 0.1 to 5 liquid volumes of feed per hour per volume of catalyst.

The polymer product obtained from the second stage dimerization is comprised of unreacted dimers of the second stage feed mono-olefins and also some higher molecular weight polymers. This polymer product is subjected to fractional distillation or to some other separation means to recover the total dimer fraction from the unpolymerized feed material and the polymers of higher molecular weight than dimers, i.e., trimers, tetramers, etc. The dimer product of this second stage dimerization is relatively linear in character, generally containing to by weight of dimers which are straight-chained or branched-chain olefins containing a single branched substituent. These dimers have the saturated general formula Ra R1C( 30CRi wherein the total number of carbon atoms is 8 to 16 and wherein R and R may be hydrogen or a n-alkyl hydrocarbon group of 4 to 12 carbon atoms and R may be hydrogen or a n-alkyl hydrocarbon group selected from the group consisting of methyl, ethyl and propyl.

The particularly preferred dimer product of the second stage dimerization is one in which the dimers are of 12 carbon atoms and which is comprised of 15 to 55% by weight of methyl undecenes, 25 to 85% by weight of ndodecenes and 1 to 10% by weight ethyl decenes. This preferred product is generally obtained by using propylene as the feed to the first stage dimerization and then recovering from the first stage dimerization product the hereinabove discussed and defined preferred feed to the second stage dimerization.

One of the primary advantages of the present invention is that the total dimer product of the second stage dimerization is relatively linear and as such may be used in total without additional separation steps in the preparation of alkyl aromatic sulfonates which are substantially biodegradable. Also, this second stage dimer fraction finds utility in many other uses requiring relatively linear monoolefins.

The method whereby the product obtained from the second stage dimerization is separated to obtain the dimer fraction is not critical to the present invention. Practically any method of separation may be used. It is only necessary that the separation means be such as to separate relatively linear dimer fraction from the unpolymerized olefins of the feed and the polymers higher in molecular weight than the dimers.

After the relatively linear dimer fraction is obtained from the second stage dimerization, it is then reacted under alkylation conditions with an aromatic compound to form an alkyl aromatic compound. This alkylation reaction may be carried out by any of the methods known to the art. The process by which alkylation of the aromatic compound with the relatively linear dimer is carried out may include those using such catalysts as the Friedel- Crafts type catalysts such as AlCl GaCl FeCl BF TiCl SnCl ZnCl and the like as well as such other alkylation catalysts as HF, H 50 H PO on Kieselguhr. Alkylation in the presence of Friedel-Crafts type catalyst will most often be carried out in the presence of a hydrogen halide, i.e., HCl, HBr, HI, and HP. The catalyst and hydrogen halide will usually be present in a Weight ratio of 2:1 to 1:2. The alkylation also may be carried out by purely thermal alkylation means. Alkylation conditions include temperatures ranging from 0 to 425 C. and with, of course, higher temperatures being necessary for thermal alkylation. Also, elevated pressures may be utilized, especially in thermal alkylation which often uses pressures in excess of 1,000 p.s.i.g. Of course, the amount of catalyst, as well as the relative amounts of aromatic and dimer fraction, will vary considerably depending on catalyst and process conditions. Preferably, the mol ratio of dimer fraction to aromatics will be 0.5 :1 to :1 though other ratios may be used. A very practical and somewhat preferred manner of carrying out the alkylation of the aromatic compounds is that illustrated by the example hereinafter presented. Briefly described, this preferred mode of alkylating the aromatic compound with the second stage dimer comprises subjecting the dimer and aromatic compound in a mol ratio of 1:6 to a temperature of 30 to 35 C. for 30 to 60 minutes in the presence of a Friedel-Crafts type catalyst, particularly aluminum chloride, and a hydrogen halide, preferably HCl, the ratio of catalyst to hydrogen halide being 1:1. It is, of course, understood that this merely represents a preferred and practical method of alkylation and is in no manner to be construed as limiting the present invention.

The aromatic compounds which may be alkylated with the monooelfin dimer fraction in the practice of the present invention includes any of the aromatic compounds known and conventionally utilized in the preparation of detergent compositions. These aromatic compounds include aromatic hydrocarbons, both monoand poly-nuclear. The aromatic hydrocarbons are both substituted and unsubstituted aromatics. When substituted, the aromatic nucleus may have any number of substituents, though it is usually preferred that there be no more than two substituents already on the aromatic nucleus. The substituents to the aromatic nucleus may be any substituent which will not appreciably interfere with the surface activity of the finished alkyl aromatic sulfonate. Generally, it is preferred that the aromatic nucleus have no more than two alkyl substituents and that these substituents have no more than 3 carbon atoms per substituent. Among the aromatic hydrocarbons which may be alkylated with the mono-olefin dimer fraction in the preparation of biodegradable alkyl aromatic sulfonates for detergent use are the following nonlimiting examples: benzene, toluene, ethylbenzene, xylenes, iso-propyl benzene, n-butyl benzene, diethylbenzenes, naphthalene, methylnaphthalenes, dimethylnaphthalenes, ethylnaphthalenes, diethylnaphthalenes, diphenyl, methyldiphenyl, dimethyldiphenyls, ethyldiphenyls, anthracene, phenanthrene, methylphenanthrene, methylanthracene, dimethylanthracene, diethylphenanthrene and the like. The particularly preferred aromatic hydrocarbons for the purposes of the present invention are benzene, toluene, naphthalene and methylnaphthalenes. In

addition to the aromatic hydrocarbons, such other aromatic compounds as those in the following nonlimiting list may be made to produce more biodegradable detergents by incorporation thereon of the present mono-olefin dimer fraction as an alkyl substituent. These aromatic compounds include phenols, cresols, xylenols, lower alkylated phenols, phenol ethers, diaryl ethers, naphthols, naphthol ethers, phenyl phenols, and the like.

The sulfonation of the alkyl aromatic hydrocarbon may be accomplished by any number of methods. Useful methods include those wherein the sulfonating agents are sulfuric acid, anhydrous sulfur trioxide, chlorosulfonic acid or such special reagents as sulfuric acid, acetic acid anhydride, sulfur trioxide-pyridine, sulfur trioxide-dioxane and the like. Generally, it would be preferred to use sulfuric acid of a strength of to 80%. The sulfonating agents generally are used in a molar equivalent to the alkyl aromatics being sulfonated. However, if desired, an excess of sulfonating agent may be used. Sulfonation may be carried out at tempenatures ranging from C. and lower up to 60 C. and higher. After sulfonation is complete, the product is neutralized with an alkali. A very practical and somewhat preferred method of sulfonating the alkyl aromatic compound is that illustrated by the example hereinafter presented. This somewhat preferred method comprises treating the alkyl aromatic compound for 5 to 7 minutes with 20% oleum at a temperature of 47 to 53 C. while maintaining vigorous agitation, thereafter lowering the temperature to 37 to 43 C. for about 40 to minutes and adding water and subsequently recovering the sulfonic acid layer and thereafter neutralizing wi;h an alkali solution, particularly sodium hydroxide. This method is only a preferred method and is in no manner limiting to the present invention.

In order to further describe and to illustrate the present invention, the following examples are presented. These examples are in no way to be construed as limiting the present invention.

EXAMPLE I In order to demonstrate-the utility of the present invention, a continuous polymerization run was carried out under the conditions described below using propylene having the composition 97% by weight propylene and 3% by weight propane. The run was carried out in the presence of 2-bromopropane as a modifying compound. The following table presents the conditions of the run and the results obtained therefrom.

Conditions:

Amount of modifier "mole percent 1 Pressure p.s.i.g 3000 Temperature C 450 LHSV 36 Average feed rate g./min- 5.6 Results:

Conversion to liquid product weight percent 16.0 Ratio straight-chain to branched-chain 6.16 Analysis of product, weight percent:

C None C 72.1 C C None 9 21.9 C10, C11 None C12 plus The product obtained in the above polymerization run is fractionated in a column of approximately 25 theoretical plates to obtain a C fraction. This fraction has the following composition and represents approximately 72% by weight of the total product.

Component: Weight percent Branched hexenes 3.7 Linear hexenes 96.3

This faction represents the relatively linear dimer fraction obtained from the thermal dimerization of propylene.

A second stage dimerization catalyst was prepared by adding approximately 300 ml. of concentrated ammonium hydroxide to approximately 300 grams of a commercial grade (BPL) of activated carbon. All of the ammonium hydroxide was absorbed. The ammonium hydroxide treated activated carbon was dried for approximately two hours at about 130 C. Next, the dried carbon was immersed in a solution of approximately 200 grams of cobalt nitrate hexahydrate in 250 ml. of demineralized water. The cobalt nitrate impregnated carbon was then dried at a low heat for approximately 3 hours until there was no visible liquid or water on the carbon and placed under vacuum for about 18 hours at a temperature of C. The dried cobalt nitrate impregnated carbon was immersed in approximately 500 ml. of concentrated ammonium hydroxide which was rapidly absorbed. This catalyst was then dried to visible dryness and placed under vacuum at 120 C. for 25 hours. As a final step, the catalyst was activated by heating at a temperature of 475 C. in the presence of a nitrogen flow for 2 hours. This catalyst contained approximately 13.5% by weight of cobalt, calculated as cobalt oxide.

Approximately 56.2 grams of this catalyst were placed in the reactor of the same dimensions as described above.

13 Approximately 3,926 grams of a fraction of the composition as set out above was passed through this catalyst bed at a rate of 0.67 ml. per minute. The catalyst bed was maintainedat a temperature of approximately 150 C. and at a pressure of approximately 300 p.s.i.g. The polymer fraction recovered was subjected to distillation and approximately 251 grams of C dimer was obtained.

Alkylation was carried out by placing approximately 175.5 grams of dry benzene in a cylindrical glass reactor equipped with a cooling coil therometer well and means for agitation. Next, anhydrous hydrogen chloride was bubbled into the reactor for approximately 7 minutes. To this mixture was added approximately 3.2 grams of anhydrous aluminum chloride. Next, approximately 100 grams of the above described C dimer fraction was added over a period of minutes to the benzene-catalyst mixture. Continuous agitation was maintained throughout the addition of the olefin inaterial and the temperature was maintained between 3035 C. throughout this period. After completion of the addition of the olefin, the reaction mass was allowed to age for approximately 15 minutes. The alkylation mass was then allowed to settle without agitation for one hour and the lower catalyst complex layer separated from the reaction mass. The remaining alkylated liquor was then washed with an equal volume of tap water.

Approximately 259 grams of the washed alkylated liquor was distilled batchwise through a /2 inch diameter packed column 12 inches in height. Benzene was recovered at atmospheric pressure at a 1:1 reflux ratio from the distillation. After removal of the benzene, the distillation was continued under reduced pressure. The Alkylbenzene product fraotion was obtained within the boiling range of 123 C. to 135 C. at 2 mm. Hg. Approximately 83.7 grams of alkylbenzene was recovered.

Approximately 75 grams of the distilled alkylbenzenes were charged to a 250 ml. flask. To this was added approximately 105 grams of oleum. The oleum was added over a 6 minute period while maintaining vigorous agitation and while maintaining a temperature of 50i3 C. After the addition of the oleum was complete the temperature was lowered to 40:3 C. and held for approximately 45 minutes. To this mixture was then added approximately 16.5 ml. of distilled water at such a rate that the temperature of the mixture could be held below 65 C. After the Water was added, agitation was stopped and the sulfonation mass transferred to a centrifuge tube and centrifuged for 30 minutes. The lower spent acid layer was separated and the sulfonic acid layer dissolved in 750 ml. of 80% iso-propanol. The solution was then neutralized to a pH of 7.0 to 9.0 with a sodium hydroxide solution. The resultant mixture was filtered to remove solid Na SO and the remaining solution dried to obtain alkylbenzene sulfonate.

EXAMPLE II In order to demonstrate the efficacy of the present invention, the alkylbenzene sulfonate prepared in accordance with the present invention was compared in biodegradability with a conventional alkylbenzene sulfonate. The conventional alkylbenzene sulfonate used as a standard is that most extensively used in present day detergents which is an alkylbenzene sulfonate prepared from propylene tetramer. The propylene tetramer was obtained by the commonly used process for polymerizing propylene which is the polymerization of propylene over a phosphoric acid catalyst as set out in US. Patent No. 2,075,- 433. The method for preparing an alkylbenzene sulfonate from the tetramer was substantially the same as the alkylation and sulfonation procedures set about above. In comparing the conventionally prepared propylene tetramer derived alkylbenzene sulfonates with an alkylbenzene sulfonate prepared in accordance with the present invention, the River Water Test was used. This test is a comparison type test and as such is indicative of the relative rates of biological decomposition of any number of different compounds being tested. The specific river Water used is not critical but due to the variance of type of bacteria in rivervwater and the day-t-o-day differences in bacterial concentration, portions of the same river water sample should be used for all comparison tests. The river water test comprises mixing 5 to 10 parts per million of alkylbenzene sulfonates with a very dilute culture of soil organisms contained in a sample of river water, and then periodically determining the alkylbenzene sulfonate content of the river water. The concentration of alkylbenzene sulfonate in the river water is determined by the methylene blue test, which comprises introducing methylene blue into a sample of the alkylbenzenesulfonate containing river water, thereby producing a salt of the alkylbenzene sulfonate with the methylene blue. This salt is then extracted with an organic solvent such as chloroform and the solution color measured. The methylene blue analysis used herein is described in The Analyst, vol. 82, 826-827 (1957). The rate and amount of the reduction of concentration of alkylbenzene sulfonate in the mixture is a comparative measure of its suceptibility or, conversely, resistance to bacterial attack.

A sample of river water was obtained and separated into two equal portions, each in a separate vessel. To one of these portions was added an amount of alkylbenzene sulfonate A, the alkylbenzene sulfonate prepared in accordance with the present invention, sufficient to bring about a concentration of 7.5 parts per million of the alkylbenzene sulfonate in the river water. To the other portion of the river Water was added alkylbenzene sulfonate B, the dodecylbenzene sulfonate prepared from propylene tetramer obtained from the conventional phosphoric acid polymerization of propylene. The amount of this conventional dodecylbenzene sulfonate added Was sufficient to bring about a concentration of 8.7 parts per million of the conventional dodecylbenzene sulfonate in the river water. The concentration of the alkylbenzene sulfonates in the river water was then determined at 0, 7, 21 and 35 days. The following table summarizes the data thus obtained.

Alkylbenzene Sultanate A 7. 5 4. 6 0.1 Alkylbenzene sulfonate B 8. 7 5. 5 2. 1

The present invention is further exemplified by an alkylbenzene sulfonate prepared from a C olefin fraction obtained by using a reaction system wherein the system used in the first stage dimerization is the same as that described in Example I, but wherein the catalyst used in the second stage dimerization is prepared as follows: An activated carbon is impregnated with a salt of cobalt, dried and thereafter activated at a temperature of approximately 475 C. The olefin fraction was obtained by the polymerization of propylene in a first stage dimerization to form a polymer product which was separated to obtain a relatively linear dimer fraction. This relatively linear dimer fraction was subjected to polymerization in a second stage dimerization to form a second dimer fraction which was then used to alkylate benzene. The alkylenebenzene so obtained was sulfonated and neutralized to obtain an alkylbenzene sulfonate. The alkylbenzene sulfonate so obtained is substantially more biodegradable than the conventional dodecylbenzene sulfonate described in the above Example II.

The present invention is further illustrated by other alkyl aromatic compounds such as naphthalenes, mixed xylenes, ortho-xylene, meta-xylene, para-xylene, ethylbenzene, methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene, and particularly by the preparation of an alkyl aromatic sulfonate using as the aromatic hydrocarbon, toluene. The alkyl aromatic sulfonate so prepared are significantly more susceptible to biological decomposition than other similar conventional alkyl aromatic compounds.

The present invention is still further illustrated by the use of modifying agents in the first stage dimerization such as l-bromohexane, l-chloropropane, H-BR, benzyl bromide, bromobenzene, Z-naphthalenethiol, tert-octylmercaptan and sulfur. The alkyl aromatic sulfonates prepared from dimers obtained through the use of these modifying agents in the first stage dimerization are significantly more susceptible to biological decomposition than are similar conventional alkyl aromatic compounds.

What is claimed is:

1. A process for the preparation of olefin hydrocarbons suitable for the preparation of alkyl aromatic compounds susceptible to biological decomposition which comprises subjecting in a first polymerization zone normally gaseous mono-olefin hydrocarbons to temperatures of from approximately 250 C. to the cracking temperature of the hydrocarbon in the feed and pressures of greater than 200 p.s.i.g. in a thermal reaction zone and in the presence of a modifying agent Which under the conditions of the thermal reaction zone will form a compound selected from the group consisting of hydrogen chloride, hydrogen bromide, hydrogen iodide, hydrogen sulfide and combination thereof, said modifying agent as a hydrogen halide or hydrogen sulfide being present in the amount of approximately 1:10 to 1:500 moles of the modifying agent per mole of mono-olefin hydrocarbon in the feed, thereby forming a polymer fraction, separating said polymer fraction to obtain a fraction comprised of relatively linear dimers of the normally gaseous monoolefin hydrocarbons, said dimers having 4 to 8 carbon atoms, contacting said relatively linear dimer fraction in a second polymerization zone at a temperature of to 250 C. and a pressure of atmospheric to 2,500 p.s.i.g., with an activated carbon supported cobalt oxide catalyst activated in an inert atmosphere at a temperature of 400 to 575 C. to form a second polymer fraction, said cobalt oxide catalyst containing approximately 2 to 50% by weight of cobalt as an oxide, separating said polymer fraction to obtain a fraction comprised of relatively linear mono-olefin dimers of olefin hydrocarbons in the feed to the second polymer fraction, said dimers being of 8 to 16 carbon atoms.

2. The process of claim 1 wherein the normally gaseous mono-olefin is propylene.

3. The process of claim 1 wherein the thermal reaction zone is maintained at a temperature of from approximately 325 to 475 C. and a pressure of at least 1000 p.s.1.g.

4. The process of claim 1 wherein the modifying agent is a compound selected from the group consisting of mono-halogen substituted hydrocarbons of no more than 6 carbon atoms, di-halogen substituted hydrocarbons of no more than 6 carbon atoms, hydrogen halides and combinations thereof, wherein the halogen present is one selected from the group consisting of bromine, chlorine, and iodine.

5. The process of claim 1 wherein the modifying agent is selected from the group consisting of elemental sulphur, sulphur bearing compounds and combinations thereof.

6. The process of claim 1 wherein the amount of modifying agent used is approximately 1:50 to 1:100 moles of the modifying agent as a hydrogen halide or hydrogen sulfide per mole of mono-olefin hydrocarbon in the feed.

7. The process of claim 1 wherein the second polymerization catalyst is activated in an inert atmosphere selected from the group consisting of nitrogen, propylene, carbon dioxide, helium, argon, and mixtures thereof.

8. The process of claim 1 wherein the second polymerization zone is maintained at a temperature of to 200 C. and a pressure of 10 to 400 p.s.i.g.

9. The process of claim 1 wherein the amount of cobait is an oxide present in the second polymerization catalyst is approximately 12 to 30% by weight.

References Cited STATES PATENTS BERNARD HELFIN, Primary Examiner.

H. ROBERTS, Assistant Examiner. 

1. A PROCESS FOR THE PREPARATION OF OLEFIN HYDROCARBONS SUITABLE FOR THE PREPARATION OF ALKYL AROMATIC COMPOUNDS SUSCEPTIBLE TO BIOLOGICAL DECOMPOSITION WHICH COMPRISES SUBJECTING IN A FIRST POLYMERIZATION ZONE NORMALLY GASEOUS MONO-OLEFIN HYDROCARBONS TO TEMPERATURES OF FROM APPROXIMATELY 250*C. TO THE CRACKING TEMPERATURE OF THE HYDROCARBON IN THE FEED AND PRESSURES OF GREATER THAN 200 P.S.I.G. IN A THERMAL REACTION ZONE AND IN THE PRESENCE OF A MODIFYING AGENT WHICH UNDER THE CONDITIONS OF THE THEMAL REACTION ZONE WILL FORM A COMPOUND SELECTED FROM THE GROUP CONSISTING OF HYDROGEN CHLORIDE, HYDROGEN BROMIDE, HYDROGEN IODIDE, HYDROGEN SULFIDE AND COMBINATION THEREOF, SAID MODIFYING AGENT AS A HYDROGEN HALIDE OR HYDROGEN SULFIDE BEING PRESENT IN THE AMOUNT OF APPROXIMATELY 1:10 TO 1:500 MOLES OF THE MODIFYING AGENT PER MOLE OF MONO-OLEFIN HYDROCARBON IN THE FEED, THEREBY FORMING A POLYMER FRACTION, SEPARATING SAID POLYMER FRACTION TO OBTAIN A FRACTION COMPRISED OF RELATIVELY LINEAR DIMERS OF THE NORMALLY GASEOUS MONOOLEFIN HYDROCARBONS, SAID DIMERS HAVING 4 TO 8 CARBON ATOMS, CONTACTING SAID RELATIVELY LINEAR DIMER FRACTION IN A SECOND POLYMERIZATION ZONE AT A TEMPERATURE OF 0 TO 250*C. AND A PRESSURE OF ATMOSPHERIC TO 2,500 P.S.I.G., WITH AN ACTIVATED CARBON SUPPORTED COBALT OXIDE CATALYST ACTIVATED IN AN INERT ATMOSPHERE AT A TEMPERATURE OF 400 TO 575*C. TO FORM A SECOND POLYMER FRACTION, SAID COBALT OXIDE CATALYST CONTAINING APPROXIMATELY 2 TO 50% BY WEIGHT OF COBALT AS AN OXIDE, SEPARATING SAID POLYMER FRACTION TO OBTAIN A FRACTION COMPRISED OF RELATIVELY LINEAR MONO-OLEFIN DIMERS OF OLEFIN HYDROCARBONS IN THE FEED TO THE SECOND PLOLYMER FRACTION, SAID DIMERS BEING OF 8 TO 16 CARBON ATOMS. 